#include<algorithm>
#include<iostream>
#include<vector>
#include<string>
using namespace std;
int main()
{
	int n;
	while (cin >> n)
	{
		vector<bool>arr(n + 1, false);
		int temp = n / 2;
		for (int j = 1; j <= n; j++)
		{
			for (int i = j; i <= n; i += j)
			{
				arr[i] = !arr[i];
			}
		}
		int num = 0;
		for (int i = 1; i <= n; i++)
			if (arr[i])num++;
		cout << num << endl;
	}
	return 0;
}
